Pirsa: 12060061 - Quantum Limits to the Measurement of Spacetime Geometry


Seth Lloyd

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This talk analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured.  By applying the fundamental physical bounds to measurement accuracy ensembles of clocks and signals, as in the global positioning system, I present a covariant version of the quantum geometric limit, which states that the total number of ticks of clocks and clicks of detectors that can be contained in a four volume of spacetime of radius R and temporal extent  is less than or equal to RT divided by the Planck length times the Planck time. The quantum  geometric bound limits the number of events or `ops' that can take place in a four-volume of spacetime and is consistent with and complementary to the holographic bound which limits the number of bits that can exist within a three-volume of spacetime.
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